Send In The Clowns

Charlotte Boan delves into the weird and wonderful world of the anemonefish

This feisty little nipper must be one of the best-loved marine creatures. It’s hopelessly cute and provides endless entertainment for anyone with time to stop and watch.

There are 28 known species of clownfish, all of which live in shallow water, no deeper than 50m. According to scientific classification, there is only one true clownfish: the star of FindingNemo itself, Amphiprion percula. The rest are officially anemonefish, however, back in the mists of time, a diver started referring to all anemonefish as clownfish, and most of us have followed suit.

The typical life of a clownfish commences with the hatching of the larvae, where it is born as a male. For a few weeks ocean currents sweep around the newly born as it feeds on the plankton. If the clownfish is lucky enough to survive this long (many are munched before they find safety), it’s time for the maturing fish to settle in its first home – a host anemone.

Clark's anemonefish - Amphiprion clarkii

False clownfish - Amphiprion ocellaris

False clownfish - Amphiprion ocellaris

Pink skunk clownfish - Amphiprion perideraion

Tomato clownfish - Amphiprion frenatus

Of all the 1,000 species of sea anemones found throughout the world’s oceans, only ten are prepared to accommodate the clownfish. In a yet-to-be resolved biological mystery, clownfish are somehow covered in mucus that protects them against the sting of their host anemone. One theory suggests that the fish itself produces the mucus from chemicals inside its body. Another maintains that the clownfish rub themselves against the anemone tentacles during elaborate dances, smearing anemone mucus over themselves and in a way becoming part of the anemone. The clownfish and anemone partnership is a classic example of a symbiotic relationship. What does each of them get out of it? For the clownfish, the stinging tentacles are a place to take refuge without fear of attack. In turn, the anemone benefits from having a fearless bodyguard which will attack any fish that would devour the anemone given the opportunity.

But the puzzle doesn’t end there. Imagine a house where the female is ‘head honcho’, with a smaller-sized male at her side to breed and a couple of unrelated, smaller-still clownfish to share the nest. The female lays her eggs under or near the anemone, which are then tended by the dominant male while she protects the home. But, here comes the strange part. When the dominant female dies, the dominant male automatically changes sex and becomes the dominant female. When this happens, the others grow in size and take a step up in the hierarchy. The fish only grow bigger when the larger fish above them in the pecking order dies.

It all boils down to the importance of territory on a crowded coral reef: anyone who has tried to get too close to a clownfish will know that they are very protective of their community. They chase off any clownfish that doesn’t fit into the hierarchy and anyone else who happens to invade its territory, no matter the size of the intruder. Some say that if this fish grew to a giant size overnight, it would probably be the most dangerous animal in the sea.

Clowning around...

Papua New Guinea: if don’t find one here, you’re diving in the blue. This is the most abundant area by far, with a staggering ten different types of clownfish recorded in one location.

Philippines: every dive site worth its salt is home to anemonefish.

Sipadan: one of the world’s favourite dive spots, off the coast of Borneo. Here, six varieties of clownfish are found in close proximity.

Great Barrier Reef: There are five known varieties that live in the world’s largest reef.

Red Sea: an area filled with endemic species, the Red Sea plays host to only one variety of clownfish, Amphiprion bicinctus. It is found on a number of different host anemones.

The rest: several locations, such as Madagascar, Seychelles, Oman Maldives and Mauritius, have their own indigenous species.

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